VERSATILE DISTRIBUTION TRANSFORMER

• US 20100315190A1
• Filed: 06/11/2010
• Published: 12/16/2010
• Est. Priority Date: 06/11/2009
• Status: Active Grant

• Current Assignee: Hitachi Energy Limited
• Original Assignee: ABB Research Ltd. (ABB Ltd.)
• Inventors: Haj-Maharsi, Mohamed Y., Lanoue, Thomas J.
• Granted Patent: US 8,013,702 B2
• Time in Patent Office: Days
• US Class Current: 336/192
• CPC Class Codes: H01F 27/02 Casings
• CPC Class Codes: H01F 27/40 Structural association with built-in electric component, e.g. fuse
• CPC Class Codes: H01F 27/42 Circuits specially adapted for the purpose of modifying, or compensating for, electric characteristics of transformers, reactors, or choke coils circuits for controlling transformers, reactors or choke coils, for the purpose of obtaining a desired output H02P13/00; impedance networks H03H
• CPC Class Codes: H01F 30/12 Two-phase, three-phase or polyphase transformers
• CPC Class Codes: H02M 5/4585 having a rectifier with controlled elements

Abstract

A versatile distribution transformer having an electromagnetic transformer and a power electronic module is provided. A pocket having connectors electrically connected to at least one winding structure of the electromagnetic transformer is mounted above the electromagnetic transformer. The power electronic module is removably mounted in a cavity of the pocket. The power electronic module includes a plurality of semiconductor switching devices and a plurality of connectors adapted to slidably engage the connectors of the pocket. The power electronic module is movable between a removed position, wherein the power electronic module is located outside the pocket, and an installed position, wherein the power electronic module is disposed in the cavity of the pocket and the connectors of the power electronic module engage the connectors of the pocket so as to electrically connect the power electronic module to the at least one winding structure.

Claims

1. A distribution transformer having a primary side for receiving input voltage and current from a source and a secondary side for providing output voltage and current to a load, the distribution transformer comprising:

a ferromagnetic core;

at least one winding structure, each winding structure comprising a primary winding for connection to the source and a secondary winding for connection to the load;

a pocket defining a cavity and having connectors electrically connected to the at least one winding structure, the connectors being disposed in the cavity;

a power electronic module operable to reduce variations in the output voltage of the distribution transformer, the power electronic module being removably mounted in the cavity of the pocket, the power electronic module comprising a plurality of semiconductor switching devices and a plurality of connectors adapted to slidably engage the connectors of the pocket, the power electronic module being movable between a removed position, wherein the power electronic module is located outside the pocket, and an installed position, wherein the power electronic module is disposed in the cavity of the pocket and the connectors of the power electronic module engage the connectors of the pocket so as to electrically connect the power electronic module to the at least one winding structure.

2. The distribution transformer of claim 1, wherein the power electronic module is further operable to control the power factor on the primary side of the distribution transformer.

3. The distribution transformer of claim 1, wherein the pocket is mounted above the core and the at least one winding structure.

4. The distribution transformer of claim 1, wherein the distribution transformer further comprises:

a tank defining an interior space containing the core and the at least one winding structure;

a dielectric fluid disposed in the interior space of the tank such that the core and the at least one winding structure are immersed in the dielectric fluid.

5. The distribution transformer of claim 4, wherein the pocket extends into the interior space of the tank.

6. The distribution transformer of claim 5, wherein at least a portion of the pocket is immersed in the dielectric fluid.

7. The distribution transformer of claim 6, wherein the pocket is secured to a top wall of the tank and the power electronic module is vertically movable into and out of the cavity of the pocket.

8. The distribution transformer of claim 1, wherein the distribution transformer is a dry transformer and further comprises a structure for holding the core.

9. The distribution transformer of claim 8, wherein the pocket is supported on the structure, above the core and the at least one winding structure.

10. The distribution transformer of claim 9, wherein the power electronic module is vertically movable into and out of the cavity of the pocket.

11. The distribution transformer of claim 1, further comprising an interlock system that prevents the power electronic module from being moved to or from the installed position when power is provided to the at least one winding structure.

12. The distribution transformer of claim 10, wherein the interlock system comprises at least one electromagnetic actuator operable to move a retaining pin between an extended position and a retracted position, wherein when the retaining pin is in the extended position, the retaining pin prevents the movement of the power electronic module from the removed position to the installed position and from the installed position to the removed position.

13. The distribution transformer of claim 1, wherein the at least one winding structure comprises three winding structures for three phases of power, respectively.

14. The distribution transformer of claim 13, wherein each of the winding structures further comprises an auxiliary secondary winding.

15. The distribution transformer of claim 14, wherein the power electronic module comprises three AC-AC converters for the three winding structures, respectively, each AC-AC converter comprising:

a first switching bridge connected to the auxiliary secondary winding of the winding structure that corresponds to the AC-AC converter, the first switching bridge comprising a plurality of the semiconductor switching devices;

a second switching bridge connected in series with the secondary winding of the winding structure that corresponds to the AC-AC converter, the second switching bridge comprising a plurality of the semiconductor switching devices;

a DC bus connected between the first and second switching bridges; and

a controller operable to control the first and second switching bridges.

16. The distribution transformer of claim 15, wherein the semiconductor switching devices comprise insulated gate bipolar transistors.

17. The distribution transformer of claim 14, wherein the power electronic module comprises a voltage source converter comprising three switching circuits and a DC bus connected in parallel, the switching circuits being connected to the auxiliary secondary windings, respectively, and comprising the semiconductor switching devices.

18. A distribution transformer system having a primary side for receiving input voltage and current from a source and a secondary side for providing output voltage and current to a load, the distribution transformer system comprising:

a ferromagnetic core;

at least one winding structure, each winding structure comprising a primary winding for connection to the source and a secondary winding for connection to the load;

a power electronic module connected to the at least one winding structure and operable to reduce variations in the output voltage of the distribution transformer, the power electronic module comprising a plurality of semiconductor switching devices; and

a housing enclosing the core, the at least one winding structure and the power electronic module, the housing comprising one or more walls having sound insulating material secured to an inner surface thereof and a plurality of vents to permit air to flow through the housing.

19. The distribution transformer system of claim 18, wherein the power electronic module comprises a plurality of switching circuits and a DC bus connected in parallel, the switching circuits being connected to the at least one winding structure and comprising the semiconductor switching devices.

20. The distribution transformer system of claim 19, further comprising at least one fan mounted proximate to one of the vents to increase the flow of air through the housing, the at least one fan being powered by DC power from the DC bus.